Aggressive bass causing headache and nausea

I definitely suggest you let them know how it makes you feel. For the longest time, I struggled to tell my mom that the way she chews gum makes me feel almost physically ill. After ignoring it, it only got worse so I told her and she tried her best to stop. If your friend understands, they’ll try to improve the environment. If anything else, maybe bring sensory friendly fidgets or things that make you comfortable (headphones, etc) while you’re in the car to make the space less stressful.